"The officers involved in the operation were suspended with pay" So they made a pothead buy coke and guns and get murdered, and got punished with a paid vacation...

That is indeed incredibly disturbing, and appears to answer my question that the police would use someone completely unrelated to the person they're trying to arrest.

There seems to have been no link between the crime Hoffman was accused of and the gang she was sent to meet, other than that they both involved drugs.